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Radiology
The Middle Cerebral Artery Doppler
Built from Obstetric Imaging
What’s inside
11 sections · 107 slides
Overview
- Scope of this presentation
- Terms used throughout
- Two clinical applications of the test
Normal fetal cerebral blood flow velocity waveforms
What the trace looks like when nothing is wrong
- Early Doppler studies of the fetal cerebral circulation
- Vessel-specific differences in Doppler indices
- Scanning plane for the fetal circle of Willis
- Middle cerebral artery waveforms across gestation
- Change in pulsatility index with gestational age
- Pulsatility index curve across gestation
- Brain growth spurts and the shape of the curve
- Pulsatility index before and after birth
- Reasons the middle cerebral artery is the vessel of choice
- Effect of colour Doppler on the examination
- Reference values for the pulsatility index
- Middle Cerebral Artery Pulsatility Index (PI) Normal Values in Pregnancy
- Middle Cerebral Artery Pulsatility Index (PI) Normal Values in Pregnancy (continued)
- Middle Cerebral Artery Pulsatility Index (PI) Normal Values in Pregnancy (continued)
- Equation behind the reference range
Middle cerebral artery Doppler and fetal anemia
How a needle test was replaced by a probe on the abdomen
- Amniotic fluid delta OD450 before Doppler
- First attempts at intrauterine transfusion
- Fetoscopy and percutaneous cord sampling
- Effect of peak systolic velocity on practice
Peak systolic velocity and the diagnosis of fetal anemia
The studies that built the 1.5 multiples of the median rule
- From pulsatility index to peak systolic velocity
- Mechanism of the velocity rise in anemia
- Velocity reference range with anemic fetuses plotted
- The 1995 reference range study
- Velocity after intrauterine transfusion
- Velocity against fetal hemoglobin
- Shape of the velocity-hemoglobin relationship
- Reference range for fetal hemoglobin
- Unnecessary cordocenteses under the older criteria
- Performance of the 1.5 multiples of the median threshold
- Serial velocity for timing cordocentesis
- Prediction of fetal hemoglobin from velocity
- Velocity compared with delta OD450
- The Diamond multicentre comparison
- Guideline recognition of the technique
- Society for Maternal-Fetal Medicine thresholds
Causes of fetal anemia followed with Doppler
Beyond red cell alloimmunization
- Most frequent causes beyond alloimmunization
- Reading the list of anemia causes
- Other Conditions Resulting in Fetal Anemia
- Other Conditions Resulting in Fetal Anemia (continued)
Technique and surveillance intervals
Getting a number you can act on, and how often to repeat it
- Steps for sampling the middle cerebral artery
- Sampling the middle cerebral artery step by step
- Sample volume at the origin of the middle cerebral artery
- Which middle cerebral artery to sample
- Angle correction and observer variability
- Interval between studies in red cell alloimmunization
- Velocity slopes by severity of fetal anemia
- Reading the velocity trend lines
- Surveillance in parvovirus B19 infection
- Spontaneous resolution of parvovirus anemia
- Peak systolic velocity in cytomegalovirus infection
- Hydrops and the decision to sample fetal blood
- Monochorionic twins and twin anemia-polycythemia sequence
- Scan schedule in monochorionic-diamniotic twins
- Conditions followed with serial velocity measurements
Middle cerebral artery Doppler and fetal growth restriction
From birth weight charts to a brain-flow measurement
- Origins of the growth restriction concept
- Estimating fetal weight and birth weight percentiles
- Population curves versus individualized growth curves
- Definition of fetal growth restriction
- Disagreement between societies on the role of the test
Middle cerebral artery indices in growth restriction
Pulsatility index, ratios, and what each one adds
- Pulsatility index and resistance index
- Effect of fetal heart rate on the pulsatility index
- Brain-sparing effect in fetal growth restriction
- Sequence of the brain-sparing response
- Middle cerebral artery waveforms in severe growth restriction
- Normalization of the pulsatility index as an ominous sign
- Limits of the pulsatility index in practice
- Cerebroplacental ratio
- Threshold disagreement for the cerebroplacental ratio
- Umbilicocerebral ratio
- Comparison of the two ratios
- Trial of the umbilicocerebral ratio
- Pulsatility index versus peak systolic velocity in growth restriction
Pathophysiology of peak systolic velocity elevation
The same high number, two different reasons
- Design of the Hanif study
- Findings in fetuses at risk for anemia
- Velocity correlations in anemic fetuses
- Velocity against hemoglobin in anemic fetuses
- Findings in growth-restricted fetuses
- Velocity correlations in growth-restricted fetuses
- Velocity against hemoglobin in growth restriction
- Two mechanisms behind one abnormal number
Waveform patterns and clinical application
Reversed flow, lost brain-sparing, and what the authors actually do
- Reversed end-diastolic flow in the middle cerebral artery
- Reversal of the brain-sparing effect
- Outcomes reported after loss of brain-sparing
- Sequence of Doppler change in late growth restriction
- Abnormal cerebral index with a normal umbilical artery
- Adverse outcome after 32 weeks' gestation
- Authors' surveillance protocol for the small fetus
- Role of each vessel in timing delivery
Summary
What to carry away
- Key points on fetal anemia
- Key points on fetal growth restriction
- Key points on technique
- References
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- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition